\setupregister
[index]
[pagesegments=1:4,
  pagemethod=page,
]
\defineprocessor [relevant] [style=italic,color=red]
\setuphead[part][placehead=yes,number=yes,incrementnumber=yes]
\starttext{

  \part{sdfds}
  \chapter {one} \section {alpha}

  x\index {whatever 1}x\index {whatever 2}x\index {whatever 2}x \page

  x\index {whatever 1}x\index {whatever 2}x\index {whatever 2}x \page

  \chapter {one}
  x\index {whatever 1}x\index {whatever 2}x\index {whatever 2}x \page
  \section {alpha}
  %%  带processor的命令。如果不显示页码。则不会应用该processor
  \index[relevant->MOUMO]{MOUMO+MOUMOsdfdsfds}
  \index[relevant->]{MOUMO+MOUMOssjys}
  Text \index{relevant->bar}text.
  Text \index{relevant->bar+rty}text.
  %%
  x\index {whatever 1}x\index {whatever 2}x\index {whatever 2}x \page

  x\index {whatever 1}x\index {whatever 2}x\index {whatever 2}x \page

  \section {beta}

  x\index {whatever 1}x\index {whatever 2}x\index {whatever 2}x \page
 
  x\index {whatever 1}x\index {whatever 2}x\index {whatever 2}x \page
  \title{ index of keyword}
  \placeindex[n=1]
} 
\stoptext 